Data-related issues in gravitatjonal wave astronomy Eric - PowerPoint PPT Presentation

Data-related issues in gravitatjonal wave astronomy Eric Chassande-Mottjn CNRS AstroPartjcule et Cosmologie Paris, France Coalescence of two black holes (credits: SXS)

Outline ● Context – direct detection of gravitational waves Eric Chassande-Mottjn ● Description of GW data products CNRS AstroPartjcule et Cosmologie Paris, France ● Highlights and lessons learned from recent workshop in Strasbourg – VO and multimessenger astronomy – Vision for the next future – open data

Sep 14, 2015 09:50:45 UTC GW signal received by the LIGO detectors First direct detection of ● gravitational waves First observation of massive ● (> 20 M sun ) stellar-mass black hole First observation of a black hole ● binary Most luminous event ever detected ● Today 19:15 CET: press conference announced Today 19:15 CET: press conference announced Webcast: https://aas.org/aas-briefing-webcast

This is a landmark discovery ● This is just the beginning ... highly signifjcant events with FARs < 1/century Expect tens or more of binary black- ● hole mergers in future runs Other types of sources? e.g., neutron ● stars Breath of science ( physics and abundance ● of compact objects and consequences on star formation, tests of GR, cosmology? ) New era of gravitational wave ● astronomy Connection to conventional/photon- ● based astronomy EM counterpart to GW is the next “big thing” Real-time alerts, open data ●

Data products and management ● Observation science data ● Time series for calibrated h(t) + data quality ● Month/year data stretches (with breaks) at 4 kHz [few 100 GB – This is a small subset of full raw data – many TB] ● Closed model with proprietary period (typ. few years) ● LIGO: data “snippet” released together with publication ● Processed data ● Alerts/events – GW event descriptor (VOevent) and skymap [small volume] – Distributed to MOU partners over a private GCN-type network – Policy: release public alerts after 4 published events (O3 ?) ● Other scientific by-products – Posterior samples from Bayesian parameter estimations

Workshop in Strasbourg May 31-Jun 1 st 2016 ~20 participants (~10 from GW, 5 countries – also robotic wide-field ● optical telescope) Discussion topics / Presentations ● – Intro on VO/tutorial on VO tools – Electromagnetic follow-up ● Alerts and VOevent ● GW skymap visualization and processing ● Galaxy catalogs – follow-up prioritization ● Time-domain observations with robotic telescopes – Open science data Summary available in last WP4 activity report ● https://www.asterics2020.eu/dokuwiki/doku.php?id=open:wp4:wp4gwstrasbourg2016

GW alerts and skymaps (1) ● Alerts from low-latency analysis Skymap from GW data 600 deg 2 – will improve with more Goal for next run: ~10 mins – detectors (Virgo) Distributed in various formats including – VOevent ● Source position reconstructed in a large error area from GW data Where to point first? – Strategy to prioritize fields in order to maximize chance of detection

GW alerts and skymaps (2) ● Help to define follow-up strategy Visualize, tile and combine skymaps – with other information (e.g., galaxy catalog for “mass targetting”) On-going collaboration to demonstrate – usage of VO tools (Multi Order Coverage Map) Skymaps will soon include a distance – estimate for binary mergers Credits: Giuseppe Greco (INFN)

LIGO Open Science Center (1) www.losc.caltech.edu ● Motivations (1 hr) – Maximize science impact – Long-term preservation – Facilitate access to collaborators (e.g., students) that are not part of the (2006-10, ~2.5 yrs total) Collaborations ● Current status h(t) @ 4kHz and 1-Hz data quality bitmask in – frame format, HDF5, txt.gz Test signals (injections), documentation, – tutorials

LOSC (3): open code and computjng iPython notebooks […] for demos using LIGO data #--------------------- # Plot the time series #---------------------- fig = plt.figure(figsize=(10,10)) fig.subplots_adjust(wspace=0.3, hspace=0.3) plt.subplot(321) plt.plot(time_seg - time_seg[0], strain_seg) plt.xlabel('Time since GPS ' + str(time_seg[0])) plt.ylabel('Strain') #------------------------------------------ # Apply a Blackman Window, and plot the FFT #------------------------------------------ window = np.blackman(strain_seg.size) windowed_strain = strain_seg*window freq_domain = np.fft.fft(windowed_strain) freq = np.arange(0, fs, 1.0/length) plt.subplot(322) plt.loglog( freq, abs(freq_domain)/4096.0) plt.axis([10, fs/2.0, 1e-24, 1e-18]) plt.grid('on') plt.xlabel('Freq (Hz)') plt.ylabel('Strain / Hz$^{1/2}$') #---------------------------------- # Make PSD for first chunk of data #---------------------------------- plt.subplot(323) Pxx, freqs = mlab.psd(strain_seg, Fs = fs, NFFT=fs) plt.loglog(freqs, Pxx) plt.axis([10, 2000, 1e-46, 1e-36]) plt.grid('on') plt.ylabel('PSD') plt.xlabel('Freq (Hz)') #------------------------- # Plot the ASD #------------------------------- plt.subplot(324) plt.loglog(freqs, np.sqrt(Pxx)) plt.axis([10, 2000, 1e-23, 1e-18]) plt.grid('on') plt.xlabel('Freq (Hz)') plt.ylabel('Strain / Hz$^{1/2}$') [...] Credits: https://www.losc.caltech.edu

Meetjng outcome and lessons learned ● New projects added on-going collaborations – Aladin customization for GW skymap handling – Glade galaxy catalog pushed to VizieR – Multi-dimensional cross-matching tool ● Provided use cases (BlackGEM telescope array) in view of VOevent std evolution – Footprints for robotic telescope pointings with time stamps Coordination for the coverage of large parts of the sky in a given time interval ● Provided use cases for time series in VO – Inclusion of time series observations in VO is still to be defined – Internal discussion in Virgo about Open Science Center. Will likely follow the LIGO model

Low latency search Four low-latency search pipelines T0+3 min = Event uploaded to DB T0+17 min = First sky map T0+2 days = Alert sent T0+2 months = Final sky map GW error region is ~600 deg 2 With Virgo on, with full sensitjvity, the GW error region reduces to ~10 deg 2

Electromagnetjc follow-up 25 teams of observers responded to the GW alert Multiwavelength: from radio to gamma-rays T0+2 days

What's next? 2010 2015 2018 future > 2020

What's next?

EM signal from BBH mergers? To explain possibly associated gamma-rays: BBH with very small separation formed in the collapse of a massive star, resulting in GRB nearly simultaneously with GWs? (Loeb, 2016) Unusually long-lived disk around BBH produces GRB at the time of coalescence? (Perna et al. 2016) If matter (“mini-disk”) exists around (B)BH Strong disk wind may be driven by radiation or magnetic fields 1.4 GHz → Fast optical transient around 22 mag in V-band may be produced when thermal photons break out of the outflow Ultra-fast flow associated with a mini-disk wind develops a blast wave which decelerates and can generate a radio afterglow From Corsi, talk at APS April 2016 Murase et al Astrophys.J. 822 (2016) L9 Yamazaki et al. arXiv:1602.05050

Past and future visibility of GW150914